Metal and plastics surfaces, for example in the automotive sector, are in many cases coated with texturing and optionally delustering coatings in order to obtain textured surfaces.
On page 51 of Farbe & Lack 7/2000 there are disclosed sample solutions for the formulation of textured coatings based on polyols (e.g. polyester polyols) and cross-linkers (e.g. polyisocyanates) according to the prior art. There are generally used as additives anti-settling agents (e.g. bentone), thixotropic agents and thickeners as well as silicone oils as effect-giving agents. In order to accelerate cross-linking, catalysts (e.g. dibutyltin dilaurate) should be added.
It is also known to use coating compositions which contain organic solvents and are based on hydroxyl group-containing binders and polyisocyanate cross-linkers and which contain pasty additives containing powdered texturing agents and delustering agents to achieve textured surfaces on, for example, plastics parts of motor vehicles, especially for automotive refinish. Ground polypropylene, for example, is used as the texturing agent. Silica, for example, may be used as the delustering agent. With the aid of the delustering agents, the coating composition used to obtain the textured surface is adjusted to the degree of gloss of the plastics surface. In order to ensure good adhesion to the plastics surface, elastifying binders are used. A problem of such systems is that dried particles on the edge of the particular packaging can fall back into the lacquer and, as so-called pinholes, can lead to disruptions in processing and to faults in the lacquer. It is not possible to remove such dried product particles by sieving because the powdered texturing agent would otherwise be removed at the same time.
An improvement of that problem is the process described in DE-A 43 17 784, according to which a powdered texturing binder is mixed with the coating composition immediately prior to application.
DE-A 43 38 265 describes the coating of substrates in strip form by the coil coating process with solvent-borne coating compositions containing highly cross-linked polymer powders, so-called microgels. Special surface effects are achieved by the use of such powders.
An object of the present invention is to provide a coating composition, its preparation and its use in the production of textured lacquer surfaces, in which it is possible to dispense with the incorporation of special texturing powdered additives.
It has been found that this object can be successfully achieved with the coating compositions of the present invention described in greater detail below.